Suxamethonium structure

In this drug class, only sucdnylcholine (succinyldicholine, suxamethonium, AJ is of clinical importance. Structurally, it can be described as a double ACh molecule. Like ACh, succinylcholine acts as agonist at endplate nicotinic cholino-ceptors, yet it produces muscle relaxation. Unlike ACh, it is not hydrolyzed by acetylcholinesterase. However, it is a substrate of nonspecific plasma cholinesterase (serum cholinesterase, p. 100). 

Metoclopramide is structurally related to orthoclopramide, a procaine derivative, and it can prolong the action of suxamethonium because of competition for cholinesterase. However, its common side effects are similar to those seen with phenothiazine derivatives. In high doses, a range of extrapyramidal symptoms may develop. The anti-emetic effects of metoclopramide are due to two main actions. Centrally, it blocks dopamine in the CTZ and peripherally, it hastens gastric emptying, abolishes irregular intestinal contractions, and increases... 

Decamethonium (Figure 6.49) was the first synthetic curare-like muscle relaxant, but has since been superseded. In tubocurarine, the two nitrogens are also separated by ten atoms, and at physiological pHs it is likely that both centres will be positively charged. Obviously, the interatomic distance (1.4 nm in tubocurarine) is very dependent on the structure and stereochemistry rather than just the number of atoms separating the centres, but an extended conformation of decamethonium approximates to this distance. Suxamethonium... 

The design of atracurium (Fig. 11.40) was based on the structures of tubocurarine and suxamethonium. It is superior to both since it lacks cardiac side-effects and is rapidly broken down in blood. This rapid breakdown allows the drug to be administered as an intravenous drip. 

The structure-activity relationship of suxamethonium-related compounds, newly synthesized phenylene-polymethylene bis-ammonium (PMBA) derivatives, has been studied in an attempt to obtain more potent... 

Fig. 1 a-f. Structural formulae of a acetylcholine, b suxamethonium, c tubocurarine, d galla-mine, e alcuronium, and f pancuronium... 

For the muscle relaxing properties of tubocurarine (D 22.1.2), for instance, only part of the complex structure of this alkaloid is necessary the presence of two quarternary iV-atoms at a certain distance from each other. This structure is mimicked in the pharmacologically similar synthetically prepared compounds of the decamethonium and suxamethonium type, in which both the quarternary A -atoms are separated either by a simple saturated carbon chain or a succinic acid-bischoline-ester residue. 

Systematic reviews Because of its fast onset of action, rocuronium is a potential alternative to suxamethonium for rapid-sequence intubation in patients with an increased risk of aspiration. Four relevant studies considering the use of suxamethonium and rocuronium in emergency departments were selected from an evidence search and a structured review performed [11 ]. For the outcomes of clinically acceptable intubation conditions and time to onset, the two agents were not statistically significantly different. Suxamethonium seems to produce conditions that have higher satisfaction scores. The authors concluded that suxamethonium remains the drug of choice for emergency department rapid-sequence induction, unless there is a contraindication. 

In suxamethonium sensitivity. Suxamethonium is a muscle relaxant used in anaesthetics and has a similar structure to acetylcholine. Normally it is hydrolysed by cholinesterase... 

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